Exposure method

ABSTRACT

An exposure method includes the steps of exposing a pattern of a reticle onto a substrate by scanning the reticle and the substrate, and by illuminating an illumination area having a slit shape on the reticle using a light from a light source, the slit shape having a longitudinal direction corresponding to a direction orthogonal to a scanning direction, and correcting an accumulated illuminance in the scanning direction at each position of the illumination area in the longitudinal direction, wherein the correcting step includes the steps of calculating a first illuminance correction amount common to plural areas on the substrate, the pattern being to be transferred to each area, and calculating a second illuminance correction amount intrinsic to each area, the correcting step correcting the accumulated illuminance based on the first and second illuminance correction amounts.

BACKGROUND OF THE INVENTION

The present invention relates to an exposure method.

A projection exposure apparatus that employs a projection optical systemto expose a reticle (mask) pattern onto a wafer has been conventionallyused. A scanning exposure apparatus has recently been reduced topractice for wide-screen exposure. The precision required for apattern's critical dimension (“CD”) uniformity becomes stricter as thefine processing develops.

In order to reduce the uneven illuminance on the screen that aggregatesthe CD uniformity, the conventional scanning exposure apparatus controlsthe exposure dose using a light blocking plate near a scan masking bladethat defines an illumination area or slit. For example, the exposuredose around the light blocking plate is set to be larger when theoptical system has a higher transmittance at the center of the opticalaxis than at the periphery.

Prior art includes, for example, Japanese Patent Application,Publication No. 9-190969, and CD Uniformity Improvement by ActiveScanner Corrections, Jan Van Schoot et al., Proceedings of SPIE, Vol.4691, SPIE, 2002, pp. 304-314 (“Schoot” hereinafter).

The conventional exposure apparatus corrects a CD error caused mainly bythe exposure apparatus, as in Japanese Patent Application, PublicationNo. 9-190969. The conventional exposure apparatus adjusts the unevenilluminance in a direction corresponding to a direction orthogonal to ascanning direction using a slit width adjusting mechanism. The slitwidth adjusting mechanism generally includes a mechanical blade, adjuststhe uneven illuminance whenever an illumination mode and a numericalaperture (“NA”) of the projection optical system are varied. The unevenilluminance among wafers and shots have not been corrected.

However, as suggested by Schoot above, it has recently been required tocorrect a deterioration of the CD error caused by processes andapparatuses other than the exposure apparatus, such as a coater, adeveloper, an etcher, and a reticle imaging apparatus. Schoot disclosesmeans for correcting the uneven illuminance by moving, in the scanningdirection, a gray filter that has a different distribution according topositions. Nevertheless, this means requires a driving mechanism similarto the reticle stage to drive the filter in the scanning direction andto correct the uneven illuminance, and would cause in a large exposureapparatus and an increased cost.

SUMMARY OF THE INVENTION

The present invention is directed to an exposure method that can highlyprecisely reduce a CD error caused by apparatuses other then an exposureapparatus.

An exposure method according to one aspect of the present inventionincludes the steps of exposing a pattern of a reticle onto a substrateby scanning the reticle and the substrate, and by illuminating anillumination area having a slit shape on the reticle using a light froma light source, the slit shape having a longitudinal directioncorresponding to a direction orthogonal to a scanning direction, andcorrecting an accumulated illuminance in the scanning direction at eachposition of the illumination area in the longitudinal direction, whereinthe correcting step includes the steps of calculating a firstilluminance correction amount common to plural areas on the substrate,the pattern being to be transferred to each area, and calculating asecond illuminance correction amount intrinsic to each area, thecorrecting step correcting the accumulated illuminance based on thefirst and second illuminance correction amounts.

A further object and other characteristics of the present invention willbe made clear by the preferred embodiments described below referring toaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scanning exposure apparatus according to one aspect of thepresent invention.

FIG. 2 is a partially enlarged sectional view of an illumination opticalsystem in the exposure apparatus shown in FIG. 1.

FIGS. 3A and 3B are schematic plane views of uneven-illuminancecorrectors shown in FIG. 2. FIG. 3C is a schematic plane view showing arelationship between the slit irradiated onto a reticle shown in FIG. 2and the scanning direction.

FIG. 4 is a schematic plane view of a first uneven-illuminance (“UI”)corrector shown in FIGS. 1 and 2.

FIG. 5 is a schematic plane view of an illustrative structure of thefirst and second UI correctors shown in FIGS. 1 and 2.

FIG. 6 is a schematic plane view of another illustrative structure offirst and second UI correctors shown in FIGS. 1 and 2.

FIG. 7 is a graph showing an illustrative synthesized, accumulatedluminance formed by the first and second UI correctors shown in FIG. 2.

FIG. 8 is a graph showing another illustrative synthesized, accumulatedluminance formed by the first and second UI correctors shown in FIG. 2.

FIG. 9 is a flowchart for explaining a UI correction method according toa first embodiment of the present invention.

FIG. 10 is a flowchart for explaining a method for calculatingcorrection amounts common to shots shown in FIG. 9.

FIG. 11 is a flowchart for explaining a method for calculatingcorrection amounts intrinsic to each shot shown in FIG. 9.

FIG. 12 is a flowchart for explaining a UI correction method accordingto a second embodiment of the present invention.

FIG. 13 is a flowchart for explaining a method for calculatingcorrection amounts intrinsic to each shot shown in FIG. 9.

FIG. 14 is a flowchart for explaining a UI correction method accordingto a third embodiment of the present invention.

FIG. 15 is a flowchart for explaining a method for calculatingcorrection amounts common to the shots shown in FIG. 14.

FIG. 16 is a flowchart for explaining a manufacture of a device, such asa semiconductor chip (e.g., an IC and an LSI), an LCD, and a CCD.

FIG. 17 is a flowchart of a detailed wafer process of step 4 shown inFIG. 16.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a scanning exposureapparatus 100 according one aspect of the present invention. Here, FIG.1 is a schematic sectional view showing a structure of the exposureapparatus 100. The exposure apparatus 100 is a scanning exposureapparatus that exposes a circuit pattern of a reticle 200 onto a wafer400 in a step-and-scan manner. The exposure apparatus 100 includes, asshown in FIG. 1, an illumination apparatus 110, a reticle stage 210 thatsupports the reticle 200, a projection optical system 300, a wafer stage410 that supports the wafer 400, a measurement apparatus 500, and acontrol system 600.

The illumination apparatus 110 illuminates the reticle 200 that has acircuit pattern to be transferred. The illumination apparatus 110includes a light source unit 120, and an illumination optical system(130, 140).

The light source unit 120 uses, as a light source, an ArF excimer laserwith a wavelength of approximately 193 nm in this embodiment. However,the light source unit 120 is not limited to the ArF excimer laser, andmay use, for example, a KrF excimer laser with a wavelength ofapproximately 248 nm, and an F₂ laser with a wavelength of approximately157 nm.

The illumination optical system uniformly illuminates a slit-shapedillumination area on the reticle 200 using the light from the lightsource, and includes an introducer 130, and a uniformizer 140.

The introducer 130 has a mechanism that makes the laser beam incoherent,and a beam shaping system that uses, for example, a beam expander havingplural cylindrical lenses. The beam shaping system shapes the beam shapeinto a desired one.

The uniformizer 140 defines a slit-shaped illumination area or slit. Theuniformizer 140 includes, as shown in FIG. 2, a fly-eye lens 141, a lens142, a scan masking blade 143, a first uneven-illuminance (“UI”)corrector 150, and an imaging optical system. Here, FIG. 2 is aschematic sectional view of the uniformizer 140.

The fly-eye lens 141 is a wavefront-splitting light integrator thatsplits the wavefront of the incident light, and forms plural secondarylight sources near the exit plane. The fly-eye lens 141 emits the lightwhile converting an angular distribution of the incident light into apositional distribution. Thus, the incident plane and the exit planehave a Fourier transformation relationship, which means an opticalrelationship between a pupil and an object plane or image plane orbetween the optical plane or image plane and the pupil plane. Thefly-eye lens 141 includes plural incorporated fine lens elements in thisembodiment. The fly-eye lens 141 may be replaced with an integratorincluding two sets of cylindrical lens arrays, an optical rod, adiffraction grating, and another light integrator.

The lens 142 maintains a conjugate relationship between the exit planeof the fly-eye lens 141 and the scan masking blade 143. As a result, thescan masking blade 143 is Koehler-illuminated with the lights from thefly-eye lens 141. The scan masking blade 143 is arranged conjugate withthe pattern plane of the reticle 200, and defines a size of the slit asa transfer area on the wafer 400 in synchronization with the stages 210and 410 during the scan exposure.

The imaging optical system includes a lens 144, a deflection mirror 145,and a lens 146, and maintains a conjugate relationship between the scanmasking blade 143 and the pattern plane of the reticle 200. The patternplane of the reticle 200 is Koehler-illuminated. The deflection mirror145 deflects the optical path by about 45° in FIG. 2. In FIG. 2, thescanning direction is the Y direction, but would be the Z directionwithout the deflection mirror 145. In order to correlate the scanningdirection and the XYZ directions irrespective of the deflection mirror,the instant application sometimes refers to a direction that isdeflected to a predetermined direction or a direction that accords withthe predetermined direction without a deflection as a “directioncorresponding to the predetermined direction.” In FIG. 2, the scanningdirection is the Y direction, but the direction corresponding to thescanning direction or slit width direction is the Z direction. Adirection corresponding to the slit's longitudinal direction is the Xdirection.

Each of the lenses 142, 144 and 146 includes plural lenses, but FIG. 2simplifies them.

The illumination optical system of this embodiment includes a first UIcorrector 150, a second UI corrector 160, and a third UI corrector 170.The correctors 150-170 serve to adjust accumulated illuminance at eachposition in the slit's longitudinal direction orthogonal to the scanningdirection. It is optional to provide the third UI corrector 170.

The corrector 150 serves to correct a CD error caused by the unevenilluminance of the exposure apparatus, and is arranged before the scanmasking blade 143 near the conjugate plane with the pattern plane of thereticle 200. FIG. 3C is a schematic plane view of a slit or illuminationarea S formed by the corrector 150. The corrector 150 has a slit widthvarying mechanism that maintains the illuminance distribution set foreach shot. The corrector 150 includes, as shown in FIG. 4, plural bladesor light blocking plates including a movable blade 151 and a fixed blade152. Here, FIG. 4 is a schematic plane view of the corrector 150. Themovable blade 151 has plural adjusting mechanisms 151 a to 151 darranged in the longitudinal direction or X direction in FIG. 4 so as toarbitrarily adjust the slit width at respective positions arranged inthe slit's longitudinal direction (X direction). The slit width is aninterval between the blades 151 and 152 in the Z direction correspondingto the scanning direction. A fixed shaft 153 is provided at the centerso as to maintain the accumulated illuminance at the slit's center. Asshown in FIG. 3C, the corrector 150 sets a slit width so that the unevenilluminance on the reticle plane is higher at the peripheral than at thecenter so as to maintain the resultant accumulated illuminance on thewafer 400 plane via the projection optical system 300.

The CD error factors caused by the exposure apparatus 100 contain A)residue aberrations of the illumination and projection optical systems,B) transmittance characteristics of the illumination and projectionoptical systems, and C) changes of the exposure condition of theillumination and projection optical systems, such as an NA of theprojection optical system, an illumination mode (e.g., a modifiedillumination). The factor A is the uneven illuminance caused by theresidue aberration in the optical design, and differs depending upon animage height and the factor C. The factor B depends mainly upon anoptical characteristic of the optical thin film, and exhibits a lowertransmittance at the screen periphery than at the screen center, whichtends to change in a rotationally symmetrical manner. Depending upon theincident angle of the light upon the mirror in the optical system, alower transmittance can change in a rotationally asymmetrical manner atthe screen periphery. In addition, a film characteristic becomes unevenon a surface of a larger lens or mirror along with the high NA scheme ofthe exposure apparatus 100, and the change of the accumulatedilluminance distorts in the level of about 0.5% to about 1%. The factorB also depends upon the image height and the factor C. The exposurecondition of the factor C varies according to products and processes.The corrector 150 corrects the uneven illuminance caused by the exposureapparatus for each exposure job.

The corrector 160 improves the CD uniformity on the wafer 400 plane, andhandles the following factors that will not be corrected by thecorrector 150. These factors contain 1) a reticle's imaging error, 2)multiple reflection flare between the projection optical system and thewafer plane, 3) an uneven thickness of the coater applied resist, 4) anuneven development of the resist by the developer, 5) uneven etching byan etcher, and 6) another uneven process by a processing unit. Thefactor 1 is known as a correction amount intrinsic to each reticlebecause a CD error amount is measured every shipped reticle. A flareamount for the factor 2 is calculated and converted into a CD error onceinformation about the reflectance of the resist applied wafer plane, thereflectance of the projection optical system, a lens shape, and anexposure shot layout on the wafer is given. Other factors can beconverted into CD error amounts from information of each processingunit. Alternatively, a pilot wafer is previously exposed and its CDerror is measured. This actual measurement provides a mixed error ofthese factors.

The corrector 160 converts a CD error amount corresponding to the abovefactors into the uneven illuminance, and correct it.

The corrector 160 provides an adjustment common to all the shots for thefactor 1. When the imaging error has approximately the same tendencyover the entire screen, the corrector 160 sets a common adjustmentamount in exposing each shot. When the factor 1 is different in thescreen, the corrector 160 changes the adjustment amount common to eachshots in synchronization with the scan exposure.

The corrector 160 provides a different adjustment according to shots forthe factors 2 to 6. On the wafer plane, there can occur a CD error thatis rotationally symmetrical in the wafer's circumferential direction, aCD error that has a gradient tendency in the entire plane, and acombination of these CD errors. When CD error variation on the waferplane is approximately the same tendency in a shot, an intrinsicadjustment amount is set to the corrector 160 in exposing each shot.When a CD error variation on the wafer plane is different in the shot,the corrector 160 varies an intrinsic adjustment amount insynchronization with the scan exposure. When the factor 1 hasapproximately the same tendency over the entire screen has a high orderdistribution that cannot be corrected by a gradient adjustment by thecorrector 160, a common adjustment amount is set to the corrector 150 inexposing each shot.

Table 1 shows items to be adjusted by the correctors 150 and 160:

TABLE 1 OFFSET CD CORR. IN 1ST 2ND SWITCHING 1ST 2ND SLIT'S LONG CORREC.CORRECTOR OF CORREC. CORREC. DIRECTION 150 160 CORRECTION 150 160 FACs.COMMON TO (HIGH — INTRINSIC 10 — A-C SHOTS ORDER) TO JOB FAC. COMMON TO(HIGH (GRAD.) INTRIN. TO 2 3 1 SHOTS ORDER) RETICLE FACs. INTRINSIC —(GRAD.) INTRINSIC — 6(n) 2-6 TO EACH SHOT TO JOB

The correctors 160 and 170 correct a CD error caused by an apparatusother then the exposure apparatus. The corrector 160 generates aresultant accumulated illuminance of a linear function with thecorrector 150. The corrector 170 generates a resultant accumulatedilluminance of a high order function with the corrector 150.

The correctors 160 and 170 are classified into two types. The first typeincludes correctors 162, 164, 172, and 174 that are arranged opticallyconjugate with the pattern plane of the reticle 200. The second typeincludes correctors 166, 168, 176, and 178 that have an opticallyFourier transformation relationship with the pattern plane of thereticle 200.

The corrector 162 is arranged near the scan masking blade 143, and thecorrector 164 is arranged near the incident plane of the fly-eye lens141. Each of the correctors 162 and 164 includes, for example, an NDfilter that optically adjusts a transmitting light quantity and changes,according to a slit position, the transmittance in the X direction inFIG. 2. For example, when the fly-eye lens 141 is viewed from the leftside in FIG. 2, the corrector 164 includes one substrate with plural NDfilter areas arranged in a matrix, each of which corresponds to eachfine lens element of the fly-eye lens 141. The ND filter can control atransmittance in a specified area by depositing a Cr film with differentthicknesses according to positions, or by changing a fine light-blockingdot pattern arrangement density according to positions.

According to the first type, in order to change the accumulatedilluminance in the slit's longitudinal direction, the correctors 162 and164 are linearly driven in the X direction corresponding to the slit'slongitudinal direction, as shown in FIG. 3A. A simple linear movementstructure is suitable for the durability and a fast movement enough forthe throughput. Here, FIG. 3A is a schematic plane view of FIG. 2 viewedfrom the Z direction, showing a driving direction for each of thecorrectors 162, 164, 172, and 174.

The corrector 166 is arranged on the pupil between lens 144 and thedeflecting mirror 145, and the corrector 168 is arranged near the exitplane of the fly-eye lens 141. Each of the correctors 166 and 168includes, for example, a filter that optically adjusts a transmittinglight quantity, and has a different transmittance that depends upon theincident angle of the light.

The lights incident upon the corrector 166 in FIG. 2 includes threelights that go up to the right, three parallel lights, and three lightsthat go down to the right. On the reticle 200, the light that goes up tothe right forms an image to the left on the reticle 200, the parallellight forms an image at the center, and the light that goes down to theright forms an image to the right. An angle of the incident light on thepupil plane corresponds to a position on the imaging plane, and anoptical filter usable for these correctors 166 and 168 can use, forexample, a band-pass filter. The band-pass filter possesses acharacteristic that has a high transmittance only to the normallyincident light having a specific wavelength, and the transmittancelowers as a difference from the incident angle increases even for thelight having the same wavelength. Assume that the peak transmissionwavelength of the band-pass filter is set slightly longer than theexposure wavelength of the exposure apparatus, the transmittance of thenormal incidence is made 80%, and the incident angle is 100. Then, thethin film that has a peak transmittance of 100% can be designed.

According to the second type, in order to change the accumulatedilluminance in the slit's longitudinal direction, the correctors 166 and168 are rotated on the XY plane around the Z-axis corresponding to theslit width direction or the scanning direction, as shown in FIG. 3B. Asimple rotation structure is suitable for the durability and a fastmovement enough for the throughput. Here, FIG. 3B is a schematic planeview of FIG. 2 viewed from the Z direction, showing a driving directionfor each of the correctors 166, 168, 176, and 178.

The corrector 160 may have a mechanical means, such as a light blockingplate, in addition to the optical filter. Referring to FIGS. 5 and 6, adescription will be given of correctors 162A and 162B that includemechanical means. Here, FIG. 5 is a schematic plane view of thecorrectors 150 and 162A. FIG. 6 is a schematic plane view of thecorrectors 150 and 162B.

The corrector 162A can adjust a gradient of the uneven illuminancechange in the slit when linearly moving in the X direction. Thecorrector 162B has a rotating shaft 163 that is rotatable around theY-axis parallel to the optical axis. The corrector 162B approximates toa rotation around the Y-axis a gradient amount of the uneven illuminancechange in the slit obtained by the linear movement in the X direction ofthe corrector 162A. The rotation is advantageous to a miniaturization ofa driving guide and a motor.

The reticle manufacturing process includes electron beam imaging,etching, and other processes. On the reticle plane, there can occur a CDerror that is rotationally symmetrical in the reticle's circumferentialdirection, a CD error that has a gradient tendency on the entire plane,and a combination of these CD errors. The corrector 170 provides arotationally symmetrical correction to the reticle imaging error. Thecorrector 170 includes, as shown in FIGS. 2, 3A, and 3B, correctors172-178 that have a conjugate or Fourier transformation relationshipwith the pattern plane of the reticle 200. For example, in FIG. 2, thecorrector 160 is the corrector 166, and the corrector 170 is thecorrector 172. Alternatively, the corrector 160 may be the corrector164, and the corrector 170 may be the corrector 172.

The corrector 170 is arranged at a position close to or different fromthat of the corrector 160. The corrector 170 includes two ND filters.The accumulated illuminance in each slit in the slit's longitudinaldirection tends to change from the slit center to the periphery. In thisembodiment, one ND filter has a cubically increasing tendency, and theother ND filter has a cubically decreasing tendency. A pair of NDfilters maintain the accumulated illuminance in the slit's longitudinaldirection constant from the slit center to the periphery at the nominalposition at which these filters' center positions or peak values of thecubic changes overlap each other. The cubic function is merelyillustrative, and the present invention does not limit a type of thefunction.

When a pair of ND filters shift to each other in the slit's longitudinaldirection, the accumulated illuminance in the slit's longitudinaldirection can be increased or decreased in a quadratic changingtendency. The corrector 174 may be arranged on a plane conjugate withthe image plane on the incident side of the fly-eye lens 141, andinclude, similar to the corrector 164, a pair of ND filters foroptically adjusting the transmitting light quantity. The number of pairscorresponds to the number of fine lens elements of the fly-eye lens 141on the XZ plane.

Each of the correctors 176 and 178 similarly includes a pair of filters.Each filter's optical characteristic changes as the filter rotates suchthat the scan accumulated illuminance cubically changes with respect toa position along a slit direction. The correctors 176 and 178 have afilter having a cubically increasing tendency of the accumulatedilluminance and a filter having a cubically decreasing tendency of theaccumulated illuminance. When the pair of optical filters angularlyshift to each other, the accumulated illuminance in the slit'slongitudinal direction can be increased or decreased in a quadraticchanging tendency.

The reticle 200 is fed from the outside of the exposure apparatus 100 bya reticle feed system (not shown), and is supported and driven by thereticle stage 210. A pattern of the reticle 200 is projected onto thewafer 400 by the projection optical system 300. The reticle 200 and thewafer 400 are located in an optically conjugate relationship.

The projection optical system 300 can use a dioptric, catadioptric, orcatoptric optical system.

The wafer 400 is fed from the outside of the exposure apparatus 100 by awafer fed system (not shown), and supported and driven by the waferstage 410. Instead of the wafer 400, a glass plate and another substratecan be used. A photoresist is applied onto the wafer 400.

The wafer stage 410 supports the wafer 400 via a wafer chuck (notshown). The wafer stage 410 serves to adjust a position in the Zdirection, a rotational direction, and an inclination of the wafer 400,under control of a control system 600. During exposure, the controlsystem 600 controls the wafer stage 410 so that the surface of the wafer400 always accords with the focal plane of the projection optical system300 with high precision.

The measurement apparatus 500 measures the illuminance and the unevenilluminance, and the control system 600 controls driving of the reticlestage 210 and the wafer stage 410.

In exposure, the introducer 130 makes incoherent the light emitted fromthe light source unit 120, properly shapes the beam shape, andintroduces the light to a uniformizer 140. The light made uniform by theuniformizer 140 Koehler-illuminates the reticle 200 in a slit-shapedillumination area defined by the scan masking blade 143. In that case,the first corrector 150 corrects CD error caused by the exposureapparatus 100, and the second and third correctors 160 and 170 correctthe CD errors caused by an apparatus other than the exposure apparatus100.

Referring now to FIGS. 7 and 8, a description will be given of acorrection method of this embodiment.

Referring now to FIG. 7, the corrector 150 adjusts the accumulatedilluminance in the slit's longitudinal direction to an accumulatedilluminance P₁ expressed by an approximately quadratic function withrespect to a position from the slit center to the periphery. Thevariable slit width of the corrector 150 shown in FIG. 4 can providethis adjustment. For the factors A to C, the corrector 150 adjusts theaccumulated illuminance as expressed by an approximately quadraticfunction with respect to a position from the slit center to theperiphery based on a state of a uniformly adjusted accumulatedilluminance.

In FIG. 7, the corrector 160 adjusts the accumulated illuminance in theslit's longitudinal direction to an accumulated illuminance P₂ that hasa reverse code to the accumulated illuminance P₁ formed by the corrector150, and is expressed by an approximately quadratic function withrespect to a position from the slit center to the periphery. Thisadjustment is obtained when the characteristic of the corrector 160 isset to the nominal or initial position. In case the accumulatedilluminance of approximately quadratic function of a position is notobtained at the initial state, the initial position is adjusted and aposition at which the accumulated illuminance can be laterallysymmetrical with respect to the slit center is reset to the nominalposition of the corrector 160.

As a result of the synthesis between the accumulated illuminances P₁ andP₂ formed by the correctors 150 and 160, the approximately uniformaccumulated illuminance is made in the slit's longitudinal direction onthe wafer plane. In practice, the corrector 160 is set to the nominalposition, and the variable slit width of the corrector 150 is adjustedso that the accumulated illuminance becomes uniform from the slit centerto the priory.

Next, in FIG. 8, the corrector 160 provides an adjustment using anaccumulated illumination P₃ that is made by laterally moving theaccumulated illumination P₂ expressed by an approximately quadraticfunction with respect to a position. As a result, a synthesizedaccumulated illuminance P₄ formed by the correctors 150 and 160 isexpressed by a linear function with respect to a position.

Referring now to FIG. 9, a description will be given of a correctionmethod of a first embodiment. Initially, an exposure Job starts, an NAstop of the projection optical system 300 is set (step 1002), and anillumination mode of the illumination optical system is set or switched(step 1004). Next, in the initial state of the corrector 160, thecorrector 150 is adjusted so as to provide a uniform accumulatedilluminance in a direction corresponding to the direction orthogonal tothe scanning direction or the slit's longitudinal direction (or Xdirection in FIG. 2) (where the accumulation direction is the Ydirection in FIG. 2) (step 1006).

Next, it is determined whether the uneven illuminance common to theshots is corrected (step 1008). With no correction, the procedure movesto the step 1020 below. If the step 1008 determines that the unevenilluminance is to be corrected, CD error correction data common to theshots is read (step 1010). The factor 1 is a major item to be corrected.The exposure apparatus automatically reads, as the correction data,inspection data of a reticle to be used (two-dimensional data expressedby an in-shot coordinate (x, y)).

Next, the uneven illuminance correction amount common to the shots iscalculated (step 1012). Initially, the CD error correction value commonto the shots is converted into the illuminance correction value. FIG. 10shows a calculation method of various offsets when the illuminancecorrection amount is the two-dimensional data expressed by the in-shotcoordinate (x, y). The laser exposure dose control uses two types ofoffsets 1 and 4 for the illuminance correction amount in the scanningdirection. The offset can be expressed, for example in terms ofpercentage.

Referring now to FIG. 10, a description will be given of the calculationmethod of the correction amount common to the shots. The offset 1 iscalculated from the one-dimensional data of y coordinate by taking onlythe slit center data (at x=0 or an average value of several points nearx=0) from the two-dimensional data expressed by the in-shot coordinate(x, y) (step 1102). Then, a high-order continuous function including agradient component expressed by the y coordinate is determined from theone-dimensional data through spline function fitting etc. so as tominimize an error (step 1104). The offset 1 is a value determined bythis function (step 1106).

The offset 4 is determined by a flow for calculating the illuminancecorrection amount in the direction orthogonal to the scanning direction.The illuminance correction amount in the direction orthogonal to thescanning direction is calculated as two types of offsets 2 and 3. First,by averaging the two-dimensional data expressed by the in-shotcoordinate (x, y) in the scanning direction, the two-dimensional data isconverted into the one-dimensional data expressed by the x coordinate(step 1108). Then, a high-order continuous function including a gradientterm expressed by the y coordinate is determined from theone-dimensional data of the x coordinate so as to minimize an error.This continuous function is separated between the gradient or linearterm and the high order (step 1109). A high-order function expressed bythe x coordinate is obtained (step 1110), and the offset 2 determined bythe high-order function is set to a driving amount for the corrector 150(step 1112). The linear function (gradient component) expressed by the xcoordinate is obtained (step 1114), and the offset 3 determined by thelinear function is set to a driving amount for the corrector 160 (step1116). The offset 4 is determined as a variation of the accumulatedilluminance at the slit center, which occurs when the offset 3 is set tothe driving amount of the corrector 160. The offset 4 is a constant termto the y coordinate (step 1118), and used for the laser exposure dosecontrol (step 1120). The offsets 1 to 4 are set to the memory in theexposure apparatus (steps 1014 to 1018).

It is now determined whether the uneven illuminance is corrected foreach shot on a wafer (step 1020). When it is determined that nocorrection is performed (step 1020), the procedure moves to step 1030below. When it is determined that the correction is performed (step1020), a correction amount intrinsic to each shot is read (step 1022).The factors 2 to 6 are to be corrected. The correction amount isacquired from CD correction data common to the wafer, and a result of apilot wafer prepared by the exposure apparatus and a process unitactually used for the process. The pilot wafer may use a CD measurementresult on the wafer plane by picking up a sample out of product wafers.Alternatively, the scatterometry may be used for the pilot wafer. Thescatterometry is a method of measuring the CD uniformity by exposing aninspection line and space (“L & S”) pattern over a wafer plane, byirradiating the inspection light, and by measuring the diffracted light.The correction data is set when the exposure apparatus automaticallyreads in-wafer CD data or when a user manually inputs a correctionamount from the result of the exposed pilot wafer.

Next, the uneven illuminance correction amount intrinsic to each shot iscalculated by converting the in-wafer CD error correction value into anilluminance correction amount (step 1024). Referring now to FIG. 11, adescription will be given of the detail of the step 1024. First, acontinuous function of a coordinate (r, θ), such as each coefficient ofthe Zernike function, is determined from the two-dimensional dataexpressed by the in-wafer illuminance correction amount so as tominimize an error (step 1202). The CD error correction amount on thewafer is affected by processing units that rotate and process, such as acoater and a developer, a continuous function of the polar coordinate(r, θ) is preferable because of high fitting precision. The Zernikefunction is an orthogonally independent function that is universallyused to indicate the wavefront aberration of the projection opticalsystem.

Next, an illuminance correction amount is calculated with a function ofthe polar coordinate (r, θ) every shot on the wafer (step 1204). Theilluminance correction amount every shot is calculated astwo-dimensional data expressed by the in-shot coordinate (x, y) Acalculation method of offsets 5-7 is as shown in FIG. 10.

That is, the offset 5 is calculated from the one-dimensional dataexpressed by the y coordinate by taking only the slit center data (atx=0 or an average value of several points near x=0) from thetwo-dimensional data expressed by the in-shot coordinate (x, y) (step1208). Then, a high-order continuous function including a gradientexpressed by the y coordinate is determined from the one-dimensionaldata through spline function etc. so as to minimize an error (step1210). The offset 5 is a value determined by this function (step 1212).

The offset 6 is determined by a flow for calculating the illuminancecorrection amount in the direction orthogonal to the scanning direction.First, by averaging the two-dimensional data expressed by the in-shotcoordinate (x, y) in the scanning direction, the two-dimensional data isconverted into the one-dimensional data to the x coordinate (step 1214).Then, a high-order continuous function including a gradient termexpressed by the y coordinate is determined from the one-dimensionaldata of the x coordinate so as to minimize an error. This continuousfunction is separated between the gradient and the high order (step1215). A high-order function component expressed by the x coordinate isobtained (step 1216). No correction is made with a value determined bythis high-order function component (step 1218). A linear function(gradient component) expressed by the x coordinate is obtained (step1220), and the offset 6 determined by the linear function is set to adriving amount for the corrector 160 (step 1222). The offset 7 isdetermined as a variation amount of the accumulated illuminance of theslit center, which occurs when the offset 6 is set to the driving amountof the corrector 160. The offset 7 is a constant term to the ycoordinate (step 1224), and used for the laser exposure dose control(step 1226).

It is sufficient to consider only the gradient component to the ycoordinate for the offset 5 and the x coordinate for the offset 6. Thisis because the CD correction amount on the wafer, which occurs due tothe influence of the processing unit, can be a monotone increasingfunction or a monotone decreasing function.

Table 2 shows a relationship between the correctors and the offsets 1-7:

TABLE 2 CD CORRECTION LASER EXPO. SWITCHING OF IN SCAN. DIREC. DOSECONT. CORRECTION OFFSET FAC. 1 COMMON TO SHOTS (HIGH INTRINSIC TO 1, 4ORDER) RETICLE FACs. 2–6 INTRINSIC TO (GRADIENT, INTRINSIC TO 5(n):GRAD., EACH SHOT CONSTANT) JOB 7(n): CONST.

The offsets 5 to 7 are set in the exposure apparatus (steps 1026, 1028).Assume that N is the number of shots on the wafer. Then, for example, Noffsets, i.e., offsets 5(1) to offset 5(N), are stored.

Next, the corrector 150 is driven into a predetermined shape (step1030). The corrector 150 drives a slit width by the offset 2. Next, thewafer 40 is fed in (step 1032). Next, the stages 210 and 410 are drivenso that the designated shot or n-th shot comes to the exposure position(step 1034). Next, the corrector 160 is driven (step 1036). Thecorrector 160 drives by an amount of the offset 3 common to the shotsadded to the offset 6(n) intrinsic to each shot.

Next follows scan exposure (step 1038). The light that has passed isprojected onto the wafer 400 at a predetermined reduction ratio due tothe imaging action of the projection optical system 300. The entire shotis exposed by synchronously scanning the reticle 200 and the wafer 400while the light source unit 120 and the projection optical system 300are fixed. By stepping the stage 410 to the next shot, all the shots onthe wafer 400 are exposed or transferred. Thereby, the exposureapparatus 100 corrects a CD error caused inside and outside the exposureapparatus, and provides a highly precise pattern transfer, and theresultant high-quality device, such as a semiconductor device, an LCDdevice, an image pickup device (e.g., a CCD), and a thin film magnetichead.

The laser exposure dose is controlled in synchronization with scanningby adjusting the pulsed energy of the light source laser, the number ofirradiation pulses or light emitting intervals, or the stage scan speed(step 1038). First, the offset 4 common to the shots added to the offset7(n) intrinsic to each shot, and set as a uniform correction amountduring scanning. In addition, the offset 1 common to the shots is addedto the offset 5(n) intrinsic to each shot, and set as a correctionamount to be synchronously controlled during scanning. The stages aredriven so that the next designated shot comes to the exposure position,and driving of the corrector 160 and scan exposure are repeated. Whenthe scan exposure to the final shot ends (step 1040), the wafer 400 isfed out (step 1042). The Job ends after the above operation is performedfor the final wafer (step 1044).

Table 3 shows a relationship between the offsets in the embodiment shownin FIG. 9:

TABLE 3 SCAN CONSTANT DURING SYNCHRONIZED SCANNING CONT. FIRST CORRECTOROFFSET 2 (or 2 + 10) — SECOND CORRECTOR OFFSET 3 + 6(n) — LASER EXPOSUREOFFSET 4 + 7(n) OFFSET 1 + 5(n) DOSE CONTROL

Referring now to FIG. 12, a description will be given of a correctionmethod of a second embodiment. Those steps in FIG. 12, which are thesame as those in FIG. 9, are designated by the same reference numerals,and a description thereof will be omitted. The correction method shownin FIG. 12 is different from that in FIG. 9 in having the steps of 1046to 1054. Instead of the steps 1024-1028, FIG. 12 includes the steps1046-1050 subsequent to the step 1022.

Referring to FIG. 13, a description will be given of a method ofcalculating a correction amount intrinsic to each shot (step 1046).Those steps in FIG. 13, which are the same as those in FIG. 11, aredesignated by the same reference numerals, and a description thereofwill be omitted. The stages are driven so that the designated shot orn-th shot comes to the exposure position. The illuminance correctionamount is calculated as an offset 8(n). First, as to a directionorthogonal to the scanning direction, a function is fitted to thetwo-dimensional data expressed by the in-shot coordinate (x, y) for Xdata for each Y coordinate (step 1228). Next, a gradient in the Xdirection is obtained for each Y coordinate using the least squaresmethod, etc. (step 1220). The offset 8(n) is obtained for the secondcorrector 160 as a function of the y coordinate (step 1230). The offset9(n) is determined as a variation amount of the accumulated illuminanceof the slit center, which occurs when the offset 8(n) is set to adriving amount of the corrector 160 (step 1234). The offset 9(n) isdetermined from a high-order continuous function including a gradientcomponent to the y coordinate (step 1232), and used for the laserexposure dose control.

Tables 4 and 5 show a relationship between the correctors and theoffsets 1-9:

TABLE 4 CD CORR. IN SWITCHING OFFSET SLIT'S LONG 1ST 2ND OF 1ST 2NDDIRECTION CORR. CORR. CORRECTION CORR. CORR. FACs. COMMON TO (HIGH —INTRINSIC 10 — A-C SHOTS ORDER) TO JOB FAC. 1 COMMON TO (HIGH (GRAD.)INTRINSIC 2 3 SHOTS ORDER) TO RETICLE FACs. INTRINSIC — (GRAD.)INTRINSIC + 8(n) 2-6 TO EACH SHOT TO JOB

TABLE 5 CD CORRECTION IN LASER EXPO. SWITCHING OF SCANNING DIRECTIONDOSE CONT. CORRECTION OFFSET FACTOR COMMON TO SHOTS (HIGH INTRINSIC TO1, 4 1 ORDER) RETICLE FACs. INTRINSIC TO EACH (GRADIENT, INTRINSIC TO5(n): GRAD., 2–6 SHOT CONSTANT) JOB 9(n): CONST.

The offsets 5, 8, and 9 are set in the exposure apparatus (steps 1048,1050). Assume that N is the number of shots on the wafer. Then, forexample, N offsets, i.e., offsets 5(1) to offset 5(N), are stored.

Two types of offsets, i.e., the offset 3 common to the shots and theoffset 8(n) intrinsic to each shot, are set to the corrector 160 fordriving. The corrector 160 uses, for corrective driving, by the amountof the offset 3 added to the offset 8(n) expressed by the y coordinateas the scanning direction in synchronization with scanning (step 1054).In the scan exposure, the laser exposure dose is controlled insynchronization with scanning while the following items are considered(step 1052). First, the offset common to the shots is set to a uniformcorrection amount during scanning. In addition, the offset 1 common tothe shots is added to the offsets 5(n) and 9(n) intrinsic to each shotfor the correction amount to be controlled in synchronization withscanning during scanning.

Table 6 shows a relationship between the offsets and the control insynchronization with scanning in the embodiment shown in FIG. 12:

TABLE 6 CONSTANT DURING SCAN SYNC. SCAN. CONTROL FIRST CORRECTOR OFFSET2 (or 2 + 10) — SECOND CORRECTOR OFFSET 3 + 6(n) OFFSET 8(n) LASER EXPO.DOSE OFFSET 4 + 7(n) OFFSET 1 + CONT. 5(n) + 9(n)

The embodiments shown in FIGS. 9 and 12 adjust the accumulated unevenilluminance in the slit's longitudinal direction caused by the factorsA-C in executing Job. With a sufficiently small variation with time ofthe factors A and B, the exposure apparatus can previously store theoffset 10 corresponding to the factor C in the Job for the slit-widthadjusting position for the corrector 150, which provides a uniformaccumulated illuminance in the initial state of the corrector 160. Theoffset 10 is set for each of plural conditions, when the Job uses pluralfactors C. For example, offset 101 to 110 are set for the factors C1 toC140.

In executing the Job to which the factor C5 is set, the offset 105corresponding to the factor C5 is read out, and the corrector 150 drivesa slit width by the amount of the offset 105 added to the offset 2 shownin Tables 3 and 4. The offset 10 is reset within a permissible timeperiod that can ignore an error amount due to the variation with time,for example, every three months. Thereby, a time period necessary forthe Job execution is shortened and the operation time of the exposureapparatus improves.

Referring now to FIG. 14, a description will be given of a correctionmethod according to a third embodiment. Those steps in FIG. 14, whichare the same as those in FIG. 9, are designated by the same referencenumerals, and a description thereof will be omitted. The correctionmethod shown in FIG. 14 is different from that in FIG. 9 in having thesteps of 1046 to 1066. Instead of the steps 1024-1028, FIG. 14 includesthe steps 1046-1050 subsequent to the step 1022. This embodimentprovides a third UI corrector 170, uses the above offset 10 (step 1056),and associates driving of the correctors 160 and 170 with scanning(steps 1054 and 1066).

Referring now to FIG. 15, a description will be given of the calculationmethod (step 1058) of a correction amount common to the shots in thisembodiment. Those steps in FIG. 15, which are the same as those in FIG.10, are designated by the same reference numerals, and a descriptionthereof will be omitted.

The illuminance correction amounts in the direction orthogonal to thescanning direction is calculated as offsets 11 and 12. First, aquadratic function is fitted to one-dimensional data in the x directionevery y coordinate so as to minimize an error (step 1122). Theone-dimensional data is obtained from the two-dimensional data of thein-shot coordinate (x, y). A gradient in the x direction every ycoordinate is obtained (step 1124), and set as the offset 11 (step1126). The quadratic function component in the x direction is obtained(step 1128), and set as the offset 12 (step 1230). An offset 13 isdetermined as a variation amount of the accumulated illuminance of theslit center, which occurs when the offset 11 is set to a driving amountof the corrector 160 and the offset 12 is set to a driving amount of thecorrector 170 (step 1234). The offset 13 is determined as a high-ordercontinuous function including a gradient component to the y coordinate(step 1132), and used for the laser exposure dose control.

Tables 7 and 8 each shows a relationship between the correctors and theoffsets 1, 5, and 8-13.

TABLE 7 CD CORR. OFFSET IN SLIT'S 1ST 2ND 3RD SWITCH. 1ST 2ND 3RD LONGDIRE. CORR. CORR. CORR. OF CORR. CORR. CORR. CORR. FACs. COMMON TO (HIGH— — INTRINS. 10 — — A-C SHOTS ORDER) TO JOB FACT. COMMON TO — (GRAD.)(2ND INTRINS. — 11 12 1 SHOTS ORDER) TO RTCL FACs. INTRIN. TO — (GRAD.)— INTRINS. — 8(n) — 2-6 EACH SHOT TO JOB

TABLE 8 CD CORR. IN LASER EXPO. SWITCHING OF SCAN. DIREC. DOSE CONTROLCORRECTION OFFSET FAC. 1 COMMON TO (HIGH INTRINSIC TO 1, 13 SHOTS ORDER)RETICLE FACs. 2–6 INTRINSIC TO (GRADIENT, INTRINSIC TO 5(n): GRAD., EACHSHOT CONSTANT) JOB 9(n): CONST.

The offsets 1, 11-13 are set in the exposure apparatus (steps 1060 to1064) The offset 10 that is previously set in the exposure apparatus isset to the corrector 150 (step 1056). Next, the stages are driven sothat the designated shot or n-th shot comes to the exposure position(step 1034). The offset 10 common to the shots is set to drive thecorrector 150. The two types of offsets, i.e., the offset 11 common tothe shots and the offset 8(n) intrinsic to each shot, are set so as todrive the corrector 160 (step 1054). Only the offset 12 common to theshots is set so as to drive the corrector 170 (step 1066). The corrector150 provides a correction amount of the offset 10. The corrector 160provides a correction amount of the offset 3 added to the offset 11expressed by the y coordinate as the scanning direction insynchronization with scanning. The corrector 170 also provides acorrection amount of the offset 12 expressed by the y coordinate as thescanning direction, in synchronization with scanning. In scan exposure,the laser exposure dose is controlled in synchronization with scanningwhile the following is considered (step 1052). The offsets 1 and 13common to the shots are added to the offsets 5(n) and 9(n) intrinsic toeach shot and set to a correction amount to be controlled insynchronization with scanning during scanning.

Table 9 shows a relationship between the offsets and the control insynchronization with scanning in the embodiment shown in FIG. 14:

TABLE 9 CONSTANT DURING SCAN. SCAN SYNC. CONTROL FIRST CORRECTOR OFFSET10 — SECOND CORRECTOR — OFFSET 8(n) + 11 THIRD CORRECTOR — OFFSET 12LASER EXPO. DOSE — OFFSET 1 + 5(n) + CONT. 9(n) + 13

The above embodiments read data an exposure result of the pilot waferusing an external apparatus, and set the data as the CD errors caused bythe factors 2 to 6 to the exposure apparatus. Of course, the pilot wafermay be directly fed in the exposure apparatus to automatically read a CDerror using a microscope etc. in the exposure apparatus, and the CDerror may be used for data for the CD correction.

The above embodiments use inspection data of a reticle ortwo-dimensional data expressed by the in-shot coordinate (x, y) for CDerror correction data common to the shots, but may obtain data from thedata of the exposed pilot wafer. In this case, in FIGS. 11 and 13, anaverage of the number of shots N of the same coordinate in the shots iscalculated using the two-dimensional data of the in-shot coordinate (x,y) for each shot. Average data of each shot or the two-dimensional dataexpressed by the in-shot coordinate (x, y) are treated as correctionamounts common to the shots, and the offsets 1 to 4 are determined. Auser may directly input the offsets 1 to 13 from a console.

Referring now to FIGS. 16 and 17, a description will be given of anembodiment of a device manufacturing method using the exposureapparatus. FIG. 16 is a flowchart for explaining a fabrication ofdevices. Here, a description will be given of a fabrication of asemiconductor device as an example. Step 1 (circuit design) designs asemiconductor device circuit. Step 2 (reticle fabrication) forms areticle having a designed circuit pattern. Step 3 (wafer preparation)manufactures a wafer using materials such as silicon. Step 4 (waferprocess), which is referred to as a pretreatment, forms actual circuitryon the wafer through photolithography using the reticle and wafer. Step5 (assembly), which is also referred to as a post-treatment, forms intoa semiconductor chip the wafer formed in Step 4 and includes an assemblystep (e.g., dicing, bonding), a packaging step (chip sealing), and thelike. Step 6 (inspection) performs various tests for the semiconductordevice made in Step 5, such as a validity test and a durability test.Through these steps, a semiconductor device is finished and shipped(Step 7).

FIG. 17 is a detailed flowchart of the wafer process in Step 4. Step 11(oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms aninsulating film on the wafer's surface. Step 13 (electrode formation)forms electrodes on the wafer by vapor disposition and the like. Step 14(ion implantation) implants ions into the wafer. Step 15 (resistprocess) applies a photosensitive material onto the wafer. Step 16(exposure) uses the above exposure apparatus 100 to expose a reticlepattern onto the wafer. Step 17 (development) develops the exposedwafer. Step 18 (etching) etches parts other than a developed resistimage. Step 19 (resist stripping) removes disused resist after etching.These steps are repeated, and multilayer circuit patterns are formed onthe wafer. This device manufacturing method can manufacture higherquality devices than ever. Thus, the device manufacturing method thatuses the exposure apparatus 100, and its resultant products alsoconstitute one aspect of the present invention.

Furthermore, the present invention is not limited to these preferredembodiments and various variations and modifications may be made withoutdeparting from the scope of the present invention.

This application claims a foreign priority benefit based on JapanesePatent Application No. 2005-354543, filed on Dec. 8, 2005, which ishereby incorporated by reference herein in its entirety as if fully setforth herein.

1. An exposure method comprising the steps of: exposing a pattern of a reticle onto a substrate by scanning the reticle and the substrate, and by illuminating an illumination area having a slit shape on the reticle using a light from a light source, the slit shape having a longitudinal direction corresponding to a direction perpendicular to a scanning direction; and correcting an accumulated illuminance in the scanning direction at each position of the illumination area in the longitudinal direction, wherein said correcting step includes the steps of: calculating a first illuminance correction amount common to a plurality of areas on the substrate, the pattern being transferred to each area; calculating a second illuminance correction amount intrinsic to each area; and setting a correction amount of the accumulated illuminance in the each area by adding the first illuminance correction amount to the second illuminance correction amount.
 2. An exposure method according to claim 1, wherein the first correction amount calculating method includes the steps of: converting two-dimensional data expressed by a coordinate in the area into one-dimensional data expressed by a coordinate along the longitudinal direction; obtaining a high order component expressed by the coordinate along the longitudinal direction; and obtaining the first correction amount that is maintained constant during scanning irrespective of a coordinate in the scanning direction, said correcting step setting the first correction amount to a first corrector that includes a pair of blades arranged on a plane optically conjugate relationship with the reticle such that an interval between the blades can be adjusted in a direction corresponding to the scanning direction.
 3. An exposure method according to claim 1, wherein the first correction amount calculating method includes the step of obtaining a gradient component expressed by a coordinate along the longitudinal direction from two-dimensional data expressed by a coordinate in the area, said correcting step setting the first correction amount to a second corrector arranged on a plane that has an optically conjugate or Fourier transformation relationship with the reticle, the second corrector being configured linearly movable in the longitudinal direction or rotatable around one axis that is parallel to a direction corresponding to the scanning direction.
 4. An exposure method according to claim 1, wherein the second correction amount calculating method includes the step of obtaining a gradient component expressed by a coordinate along the longitudinal direction from two-dimensional data expressed by a coordinate in the area, said correcting step setting the second correction amount to a second corrector arranged on a plane that has an optically conjugate or Fourier transformation relationship with the reticle, the second corrector being configured linearly movable in the longitudinal direction or rotatable around one axis that is parallel to a direction corresponding to the scanning direction.
 5. An exposure method according to claim 1, wherein the first correction amount calculating method includes the step of obtaining a high order component expressed by a coordinate along the longitudinal direction from two-dimensional data expressed by a coordinate in the area, said correcting step setting the first correction amount to a third corrector arranged on a plane that has an optically conjugate or Fourier transformation relationship with the reticle, the third corrector being configured linearly movable in the longitudinal direction or rotatable around one axis that is parallel to a direction corresponding to the scanning direction.
 6. An exposure method according to claim 1, wherein at least one of the first and second correction amounts is maintained constant irrespective of a coordinate along the scanning direction.
 7. An exposure method according to claim 1, wherein at least one of the first and second correction amounts is expressed by a function of a coordinate along the scanning direction, and said exposure method further comprises the step of controlling the at least one in synchronization with scanning.
 8. An exposure method according to claim 1, further comprising the step of correcting a laser exposure dose, which step includes the steps of: calculating a third illuminance correction amount common to the plurality of areas on the substrate; and calculating a fourth illuminance correction amount intrinsic to each area, said laser exposure dose correcting step correcting the laser exposure dose based on the third and fourth illuminance correction amounts.
 9. An exposure method according to claim 8, wherein the third illuminance correction amount calculating step includes the steps of: obtaining a high order component including a gradient component expressed by a coordinate along the scanning direction from two-dimensional data expressed by a coordinate in the area so as to set a component of the third illuminance correction amount in the scanning direction as a function of the coordinate along the scanning direction; and setting a component of the third illuminance correction amount in the longitudinal direction by canceling out an illuminance variation caused by the first illuminance correction amount.
 10. An exposure method according to claim 8, wherein the fourth illuminance correction amount calculating step includes the steps of: obtaining a gradient component expressed by a coordinate along the scanning direction from two-dimensional data expressed by a coordinate in the area so as to set a component of the fourth illuminance correction amount in the scanning direction as a function of the coordinate along the scanning direction; and setting a component of the fourth illuminance correction amount in the longitudinal direction by canceling out an illuminance variation caused by the second illuminance correction amount. 